Masking fixture for spray painting

ABSTRACT

A fixture for providing accurate placement of a mask unit with respect to parts to be spray painted. The parts are supported on a structure mounted for relative movement toward and away from the mask to provide access for insertion and removal of work pieces. Masks are detachably interengaged with the fixture with accurate placement to minimize the delay in replacing masks.

United States Patent Szczepanski June 26, 1973 MASKING FIXTURE FOR SPRAY PAINTING 3,206,322 9/1965 Morgan 118/504 x 3,380,434 4/1968 Faber 118/504 X [76] Invent szclelanslf" 9 Clancy 3,385,193 5/1968 Dougherty et al. 355/93 Grand P 1 49503 3,516,386 6/1970 Landwehretal 118/503 x [22] Filed: Dec. 27, 1971 FOREIGN PATENTS OR APPLICATIONS 21 L 212 179 632,393 11/1949 Great Britain 355/93 Primary Examiner-Morris Kaplan 118/5036; A"omey Glenn Morse n c [58] Field of Search ..l 18/500-505, 301, 48-495, [57] ABSTRACT A fixture for provldmg accurate placement of a mask unit with respect to parts to be spray painted. The parts [56] References Cited are supported on a structure mounted for relative movement toward and away from the mask to provide UNITED STATES PATENTS access for insertion and removal of work pieces. Masks 1,51 1,5 84 10/1924 Soullier 355/93 are detachably fina -engaged with the fixture with accu. i g i l g g/ 42 rate placement to minimize the delay in replacing c m1 3,109,641 11/1963 LaPierre 118/504 x masks 3,161,543 12/1964 Borders et al. 118/503 X 10 Claims, 44 Drawing Figures mtmmmzs 191s 3.741; 1 54 INVENTOR Hurry Szczeponski ATTORNEY PATENml-mzsm 3.741.154

Slit! 02 N 11 INVENTOR Hurry Szczeponski ATTORNEY 3.741.154 SIIEEI 03!! 11 7\ EIK PATENTED JUN 26 973 INI/E/VTOI? ATTORNEY Fig. 6

Harry Szc-zeponski BY 2w i m .l-lllllllllllll'IlI-lallllllllllll'llllll Fig. 7

PATENTED M26 I973 sum 0'4' 11 IIE INVENTOR Hurry Szczeponski ATTORNEY PATENTEB JUII 26 97% SEE! 07 11 INVENTOR Harry Szczepunski ark ATTORNEY mzmmmzs ms 3.741; 154

Fig. 34 Fig. 35 Fig. 36

lNl/E/VTOR Hurry Szczeponski ATTORNEY PATENTEDJUNZSIBH mi 11511 3.741.154

Fig. 40 431+ Fig 4/ 8 INVENTOR Harry Szczeponski BY M QM ATTORNEY MASKING FIXTURE FOR SPRAY PAINTING BACKGROUND OF THE INVENTION Wherever paint is applied as an industrial process, it is the usual practice to utilize spray-painting techniques. A mask is used to shield that part of the work piece which is not to receive the paint. A mask is essentially a panel with cut-out areas having a precise contour which must be held in an accurate relationship with respect to the work pieces if misplacement of the paint is to be avoided. So-called nests are essentially holding devices for the work pieces, with the nests providing a base structure which can be held with respect to the mask to assure this placement relationship. It is at this point that problems in the design of this type of equipment begin to arise. It is first necessary to provide for the insertion and removal of work pieces without extensive assembly and disassembly of the fixture components. It is also highly desirable that the mask unit be readily detachable from the fixture so that succeeding jobs requiring different masks can be accommodated with a minimum of set-up and adjustment time. A number of different arrangements for providing these features to a greater or less degree have been placed in use, and the present invention has been conceived to provide the most effective practical solution to these problems of design. I

SUMMARY OF THE INVENTION A platform for supporting work piece-holding devices is mounted on a frame for movement toward and away from a mask located with respect to the frame by a placement mechanism. The movement of the supporting platform provides an open-closed relationship for insertion and removal of work pieces, and the disem gageable placement of the masks simplifies the substitution of one mask for another as job requirements are changed. In the preferred form of the invention, the frame is rotatably mounted on a base to provide spraying access from various lateral directions. The latter feature is particularly valuable in cases where the work pieces are interengaged with the mask for application of spray to the sides of work pieces which mayapproach parallelism with respect to the direction of movement of the support mechanism toward and away from the mask.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the preferred form of the invention, with the support platform elevated to a position corresponding to the interengagement of the mask and work pieces.

FIG. 2 is a perspective view of the fixture shown in FIG. 1, rotated 90 on the base for lateral accessability.

FIG. 3 is a perspective view of the fixture illustrated in FIG. 1, rotated in an opposite direction from that shown in FIG. 2.

FIG. 4 is a perspective view on an enlarged scale over that of FIGS. 1 to 3, showing the supporting structure for the work pieces in an intermediate position between fully opened for accessability, and fully closed for the application of spray. In FIG. 4, the base structure is omitted.

FIG. 5 is an end view of the structure shown in FIG. 4, in the fully elevated position of the work-support.

FIG. 6 is a section on the plane 6-6 of FIG. 12, with the structure in the condition illustrated in FIG. 5.

FIG. 7 is a section on an enlarged scale showing the mask-locating mechanism.

FIG. 8 is a section on the plane 8-8 of FIG. 7.

FIG. 9 is a top view of the portion of a mask provided with the locating ring associated with the mechanism illustrated in FIGS. 7 and 8.

FIG. 10 is a section on the plane 10-10 of FIG. 8.

FIG. 11 is a fragmentary top view of the structure shown in FIG. 4.

FIG. 12 is a front view with respect to FIG. 1 1, FIGS. 11 and 12 being in projection.

FIG. 13 is a section on the planes 13-13 of FIG. 12.

FIG. 14 is a section on the plane 14-14 of FIG. 11. a FIG. 15 is a view of one of the stabilizing roller assemblies at the opposite ends of the fixture.

FIG. 16 is a sectional view on the plane 16-16 of FIG. 15.

FIG. 17 is a view showing the attachment of the FIG. 15-16 assembly to the work-support structure.

FIG. 18 is a section through the central portion of FIG. 17, in the free position.

FIG. 19 is a view of the structure in FIG. 18 showing the deflection of the roller assembly support to provide resilient bearing engagement.

FIG. 20 illustrates a modified form of the invention providing an adjustable placement of the mask-locating structure with respect to the frame of the machine.

FIG. 21 is a end view of the fixture illustrated in FIG.

'20, in the lowest position of the mask-placement mechanism.

FIG. 22 is a view similar to FIG. 21, in the fullyextended position of the mask.

FIG. 23 is a section through the mask-locating mechanism, taken on the plane 23-23 of FIG. 24.

FIG. 24 is a section on the plane 24-24 of FIG. 23.

FIG. 25 is a section on the plane 25-25 of FIG. 23.

FIG. 26 is a sectional elevation at one end of the complete fixture of the type illustrated in FIG. 20.

FIG. 27 is a fragmentary section on an enlarged scale of the pivot structure used in conjunction with the FIG. 26 arrangement.

FIG. 28 is a top view of a blank mask unit.

FIG. 29 is a side elevation with respect to FIG. 28, FIGS. 28 and 29 being in projection.

FIG. 30 is a section on a plane 30-30 in FIG. 28.

FIGS. 31 through 33 illustrate the successive steps in the attachment of the mask unit to the frame.

FIGS. 34 through 36 show the successive steps in the removal of the mask from the frame.

FIG. 37 is a transverse section through the lower portion of a modified form of the invention providing dualpressure actuation. FIG. 37 illustrates the mechanism in a position corresponding to low-pressure operation.

FIG. 38 is a section in side elevation with respect to FIG. 37.

FIG. 39 is a view of the mechanism illustrated in FIGS. 37 and 38 in the position corresponding to highpressure actuation.

FIG. 40 illustrates a modified form of the invention providing roll-back of the mask to establish loading and unloading clearance. FIG. 40 illustrates the device in the operative condition prepared for spraying action.

FIG. 41 illustrates the clearance position of the device shown in FIG. 40.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fixture shown in FIGS. 1, 2, and 3 includes the base 40 having end plates 41 and 42 that function as brackets providing pivotal support for the frame 43. This frame structure centers in the opposite end members 44 and 45 interconnected by the-beam 46. This beam supports the jack devices 47 and 48 responsible for the placement of the work-supporting platform 49, and its movement toward and away from the masklocating structure generally indicated at 50. FIGS. 2 and 3 illustrate the rotation of the frame in opposite directions 90 from the vertical position shown in FIG. 1, in order to provide spraying accessability. The pivotal connection providing this freedom of adjustability is best illustrated in FIG. 27, and this structure is duplicated at the opposite ends of the fixture. A threaded boss 51 is welded to the end-plates 41 and 42 of the frame, and a pivot bolt 52 traverses holes in the end members of the frame, and has threaded engagement with the boss 51. A spacing washer 53 is usually desirable, as well as a retaining washer 54. A cross-pin or cotter key 55 is recommended to maintain the desired degree'of tightness of the bolt 52 as a means of controlling the resistenceof rotation of the frame 43 with respect to the base 40, The holes in the end members 44 and 45 traversed by the bolts 52 are indicated at 56 and 57 in FIG. 4.

Referring to FIGS. 4, 5, and 6, the mask unit 58 is located laterally with respect to the frame 43 by the interaction of balls 59 and 60 with the receptacles 61 and 62, respectively. This locating mechanism is illustrated in FIGS. 7 through 10, and this structure is duplicated at the opposite ends of the fixture. The receptacles have a central recess indicated at 63 having a tendency to center itself with the curvature of the balls under pressure provided by the leaf spring 64 supported at its opposite ends by the bolts 65 and 66 in threaded engagement with the plate 67 secured to the cross member 68 of the frame. The degree of pressure generated .by the spring 64 is controlled by the degree of threaded interengagement of the boltswith the plate 67, which can be locked at any desired point by the nuts 69 and 70. The plates 67 and the upper flanges 71 of the angleshaped cross members 68 and 72 have aligned holes for freely receiving the balls 59 and 60. Downward pressure of the receptacles against the balls will therefore centerthe mask units with respect to the frame. Preferably, the receptacles have a flange as shown at 73 surrounding a cylindrical portion received within an appropriate hole in the mask unit 58. The receptacle is secured with respect to the mask preferably by welding, as" shown at 74. Incidentally, the mask 58 is shown in the drawings as a blank panel. Normally, this panel would be provided with openings of various configuration for permitting the passage of paint spray to corresponding contours of work pieces immediately underneath the mask.

The force required to hold the mask unit down against the action of the springs 64 are generated by the angle members 75 and 76 secured to the side flanges 77 and 78, respectively, of the mask unit 58. These angle members hook under the side bars 79 and 80, respectively, interconnecting the end members 68 and 72. There is sufficient lateral lost motion between the angle members and 76 and the bars 79 and 80 to accommodate the engagement and disengagement shifting illustrated in FIGS. 31 through 36. As the mask unit 58 is shifted to one side or the other, the angle member 75 and 76 will disengage from the bar, thus permitting that side of the mask to be lifted upward. Shifting in the opposite direction (after the free angle member has been lifted clear of the bar) will then result in disengaging the opposite side of the mask unit. Engagement of the mask proceeds in the reverse of this sequence of operations. Once the engagement of the mask has been brought to a point close to full centering, the pressure of the balls 59 and 60, as they attempt to enter the central recesses 63 of the receptacles, will snap the mask into a fully centered position. Since the end members 68 and 72 are secured (preferably by welding) to the angle-shaped supports 8l-82 secured to the end member 44, and the similar supports 83 and 84 secured to the end member 45, the mask is thereforelocated accurately with respect to the primary frame structure. The junction of the channel-shaped beam 46 with the end members 44 and 45 is preferably reinforced by the angle brackets 85 and 86 to unite the frame components in a rigid structure capable of maintaining the ac curate relative placement of work pieces and masks.

The work pieces are commonly placed in a nest (not shown) removably supported by the beam 49 carried by the jacks 47 and 48. The location of fastenings for maintaining the placement of the nest on the beam 49 will necessarily vary with the particular job, and these fastenings are accordingly omitted from the drawings. The construction of neststs will likewise vary with the work pieces being processed, and are essentially holding devices for maintaining the placement and orientation of the work pieces for accurate registry with the masks. Shifting of the support beam 49 from the opposite extremes of the travel of the jack units will permit the operator of the fixture to insert and remove work pieces, followed by shifting them upward for registry with the appropriate openings in the mask unit.

An equalizing mechanism is incorporated in the fix ture for assuring the equality of the movement at the four corners of the structure associated with the support beam 49. This structure is the same at the opposite ends of the fixture, and is best shown in FIGS. 6 and 11 through 14. Bearing blocks 87 are mounted across the open ends of the channel-shaped configuration of the work-support beam 49 to provide rotatable support for the short shafts 88 and 89 associated respectively with the spur gears 90 and 91. These gears are in 'mesh with each other, and with the gear racks 92 and 93, respectively secured to the side flanges of the angle members 83 and 84. The upward movement of this assembly is limited by the stop ledge 94 secured to the adjacent end member 45. The tubular shafts 95 and 96 are fixed with respect to the shafts 88 and 89, respectively, and interconnect the assembly shown in FIG. 13 with a corresponding assembly at the opposite end of the fixture. This mechanical interconnection obviously results in assuring that all four corners of the work-support beam 49 will move with respect to the frame in exactly the same degree and direction.

To remove as much lost-motion endwise with respect to the beam 49, a resilient pressure is applied against the smooth sides of the racks 92 and 93 by the rollers 97 and 98. These rollers form part of a sub-assembly shown best in FIGS. 15-19. A central block 99 supports a rod 100, which is provided with spacer tubes on opposite sides as shown at 101 and 102 in FIG. 16. The nuts 103 and 104 hold the end washers 105 and 106 against shoulders at the opposite ends of the rod 100, and the rollers 97 and 98 are respectively confined between these washers and the inner washers 107 and 108. The block 99 is held resiliently in position by the leaf spring 109 secured at its fixed end to the bearing block 87 by the bolts 110 and 111, and to the central block 99 by the bolts 112 and 113. It is preferable that this assembly be duplicated at the opposite ends of the fixture, but a fixed bearing shoe can replace the resilient assembly at one end, if desired.

The jacks 47 and 48 function as actuators for the placement of the work-supporting beam 49. The structure of these units is best shown in FIG. 14. The lower unit 114 functions as a piston, and has a base flange 115 bearing against the beam 46. The bolt 116 traverses one of the holes 1 17 in the beam 46 to secure the jack unit in position. The cylinder 118 is in telescopic relationship with the lower piston unit 114, and is closed off at its upper extremity by the cap 119 bearing against the underside of the beam 49. Appropriate conventional seals can be used at the junction of the piston with the cylinder, and pressure can be admitted into the interior passage 120 either directly through an axial passage in the bolt 1 16, or through a conventional side fitting of the type shown at 121 in FIG. 26. In the latter case, the arrangement shown in FIG. 26 of the drawings is recommended, and utilizes a radial passage 121a in the base flange 1 15, which communicates with the side passage 121b in the mounting bolt 116.

FIGS. 20, 21, and 22 show an arrangement for adjusting the height of the structure supporting the masks. The plates 122 and 123 are respectively secured to the end members 44 and 45 of the frame by bolts as shown at 124-127 in FIG. 20. The use of the plurality of holes for the bolts in both the plates 122 and 123 and in the corresponding end members of the frame provide the adjustability between the positions shown in FIG. 21 and FIG. 22.

A modified structure for maintaining the location between the mask and the fixed frame structure is illustrated in FIGS. 23-25. The ring 128 is welded to the underside of the flange of the angle-shaped cross member 129, and the bolts 130 and 131 are secured with respect to this flange by the nuts 132 and 133, respectively. The leaf spring 134 is placed under predetermined deflection by the pairs of nuts 135-136 and 137-138. Aligned holes in the mask unit 139 and in the reinforcing member 140 of less diameter than the ball 141 provide the alignment function. A cap 142 may be used to cover this opening.

FIGS. 37 through 39 illustrate an arrangement for providing a dual pressure actuation for thetixture. The final placement of the fixture with respect to the mask should be done under substantial pressure in order to assure that the mask is in proper shielding position without undesirable clearance which might distort the placement of the spray on the work pieces. The withdrawal of the work pieces from the mask produced by the lowering of the support member 49 (as a result of the lowering of the jack units 47), together with the major-portion of the return stroke become very hazardous when conducted under the high-pressure conditions required for the final placement. The downward traverse of the support member 49, and the return to a point approaching the final spraying position, are conducted under a low-pressure condition controlled by the valve mechanism illustrated in FIGS. 37 through 39. An angle bracket 143 is secured to the base flange 115 of the jack unit preferably by conventional screws, and the vertical plate 144 is secured to the vertical leg of this bracket also by conventional screws. The plate 144 is provided with a slot 145 which receives the mounting leg of the conventional valve unit 146. This leg is usually in the form of a tubular extension having exterior threading, and is locked in position along the slot 145 by the lock nuts 147 and 148. The actuator of the valve unit 146 is a cam-follower roller 149, which engages the outer surface of the cylinder 118 of the jack unit. In the position shown in FIG. 39, the follower 149 is no longer supported by the cylinder 118, resulting in the placement of the valve 146 in the position which will apply high pressure to the interior of the jack unit, thus corresponding to the final closure of the work pieces with respect to the mask. Immediately following the initiation of downward movement of the work support 49, however, the lower extremity of the cylinder 118 contacts the roller 149, and places the assembly in the position shown in FIG. 38, thus establishing lowpressure conditions for the remainder of the downward travel and for the return travel to the position shown in FIG. 39. Accidental misalignment of any of the work pieces within a mask will thus halt the movement of the support 49 with a gentle force and prevent damage to the mask. or the work pieces. It will also have the desirable effect of applying these same gentle forces in the case where the operator happens tohave his hand inadvertently in the closure area between the work support and the mask. The high-pressure conditions provided by the FIG. 39 condition can only develop after practically all clearance has been removed between the work pieces and the mask to the point that could not be reached if a work piece was mis-aligned, or if a foreign object were interposed between the mask and the work pieces.

FIGS. 40 through 44 illustrate a modified form of the invention providing a lateral movement of the mask with respect to the fixture for loading-unloading. clearance. With this arrangement, the travel of the jack units can be considerably reduced, as it is then only necessary for the jacks to provide for the relatively small motion involved in the interengagement of the work pieces with the mask. With this limitation on the travel requirements of the jacks, the overall height of the unit can be vastly reduced. Loading and unloading can also take place directly from above, without the necessity of passage of the work pieces between vertically spaced planar structures. The frame 150 supporting the mask 58 is similar to the structures shown on FIGS. 5 and 6, with the addition of the brackets 151 secured to the vertical flanges 152 of the angle members constituting the ends of the frame 150. A roller 153 is rotatably mounted on a stud 154 secured to the bracket 151 by the nut 155. An angle member 156 is secured to the plate 157 adjustably secured to the end channel 158 as previously described. The roller 153 engages the underside of the horizontal leg of the angle 156, and the I frame 150 is thus supported at the left side of the device, as shown in FIGS. 40 and 41, by the rolling engagement of the gears 160 along the racks 159. The assembly is retained in engagement with the racks by the action of the rollers 153.

The right-hand side of the mask-supporting rack 150,

as viewed in FIGS. 40 and 41, is supported by the adjustable link 162. This unit is also repeated at the opposite end of the fixture. This assembly has the outward appearance of a turn-buckle, and is pivotally connected to the flange 152 at the upper extremity, and to the base angle 163 at a selected one of the holes 164. The central tubular member 165 of the link 162 is internally threaded, receiving the threaded ends of the end fittings 166 and 167. Lock nuts 168 and 169 secure the adjusted position of the device, the length of which can be selected to assure horizontal alignment of the mask 58 in the positions shown in FIG. 40. The enlarged ends 170 and 171 of the end fittings are conventional, and are provided with bearings for receiving the securing bolts 172 and 173. It should be noted that the placement of the mask'supporting rack 150 in the operating position shown in FIG. 40 should result in a vertical placement of the axis of the links 162 with respect to the horizontal flange of the angle 156, thus resulting in a zero tendency for pressure of the work pieces into the mask to induce a lateral motion of the assembly one way or the other. Limitation of the movement of the mask-carrying rack 150 to the left, as shown on FIG. 40, is provided by an offset in the horizontal leg of the angle 156 in position to engage the portion 167 of the links 162, as shown in FIG. 43. Limitation of the motion'in the direction to the right, as shown in FIG. 41, is provided by the presence of the stop member 174, which is a short section of angular configuration mounted on the underside of the flange 156 in a position to intercept the roller 153, as shown in FIG. 41. Relative placement of the mask rack and the frame in a direction parallel to the shaft 161 is maintained by the interengagement of the rail 175 with the space between the gear 160 and the collar 176 mounted on. the shaft 161. Actuation of the device between operating and clearance positions can be manual, spring controlled, or powered.

I claim:

1. In combination with a mask device normally having openings for the passage of sprayed material, a fixture for use in conjunction with spray painting comprismg:

a frame; 1

means on said frame for disengageably supporting and locating said mask with respect to said frame; work-support means mounted on said frame for vertical movement toward and away from said masksupport means; said means being pivotally mounted about a horizontal axis which is parallel to and spaced from the work-support means whereby to permit ready access to said worksupport when the frame is pivoted away from a position overlying the work support; and

actuating means for positioning said work-support means with respect to said mask-support means.

2. A combination as defined in claim 1, wherein said mask-supporting and locating means includes flange means on said mask device disposed to interengage with portions of said frame in a selected lateral relationship of said mask with respect to said frame, and further disposed to disengage from said frame on lateral displacement from said position, said masksupporting and locating means also including resilient detent means for disengageably maintaining said selected lateral relationship.

3. A combination as defined in claim 2, wherein said detent means includes means forming a recess in said mask device, and also includes a member movably mounted on said frame and adapted to register with said mask recess, and also includes biasing means urging said member in a direction toward engagement with said recess, said flange means being further disposed to retain said mask device in position against the action of said biasing means.

4. A combination as defined in claim 3, wherein said member is a ball, and said frame has an opening adapted to only partially receive said ball, said ball being disposed primarily on the opposite side of said opening from said mask device, said biasing means including a spring urging said ball toward said opening.

5. A combination as defined in claim 4, wherein said spring is a leaf spring bearing against said ball, and supported on opposite sides of said .ball.

6. A combination as defined in claim 1, wherein said actuating means includes at least one piston-cylinder unit interposed between a portion of said frame and said work-support means.

7. A combination as defined in claim 6, wherein said piston-cylinder unit includes a cylinder portion having an end thereof in direct engagement with one of said frame or said work-support means.

8. A combination as defined in claim 1, additionally including a pair of parallel shafts rotatably mounted on said work-support means, each of said shafts having a gear fixed to each of the opposite ends thereof, and also including rack means secured to said frame and interengaged with each of said gears.

9. In combination with a mask device normally having openings for the passage of sprayed material, a fixture for use in conjunction with spray painting comprising:

a frame; means on said frame for disengageably supporting and locating said mask with respect to said frame;

said means including a carrier normally supporting said mask, a shaft rotatably mounted on said carrier a gear fixed with respect to each end of said shaft, rack means mounted on said frame and in engagernent with each of said gears, retaining means maintaining the said gears and racks in engagement, and link means connected to said frame and to said carrier at a position remote from said shaft whereby to laterally remove said mask and carrier from a position overlying said work-support means;

work-support means mounted on said frame for vertical movement toward and away from said masksupport means; and actuating means for positioning said work-support means with respect to said mask-support means.

10. A combination as defined in claim 9, wherein said link means being disposed perpendicularly to the plane rack is rectangular and said shaft is disposed adjacent of said rack means in the operative position of said one side thereof, and said link means is connected at a rack. position adjacent theopposite side of said rack, said 

1. In combination with a mask device normally having openings for the passage of sprayed material, a fixture for use in conjunction with spray painting comprising: a frame; means on said frame for disengageably supporting and locating said mask with respect to said frame; work-support means mounted on said frame for vertical movement toward and away from said mask-support means; said means being pivotally mounted about a horizontal axis which is parallel to and spaced from the work-support means whereby to permit ready access to said work-support when the frame is pivoted away from a position overlying the work support; and actuating means for positioning said work-support means with respect to said mask-support means.
 2. A combination as defined in claim 1, wherein said mask-supporting and locating means includes flange means on said mask device disposed to interengage with portions of said frame in a selected lateral relationship of said mask with respect to said frame, and further disposed to disengage from said frame on lateral displacement from said position, said mask-supporting and locating means also including resilient detent means for disengageably maintaining said selected lateral relationship.
 3. A combination as defined in claim 2, wherein said detent means includes means forming a recess in said mask device, and also includes a member movably mounted on said frame and adapted to register with said mask recess, and also includes biasing means urging said member in a direction toward engagement with said recess, said flange means being further disposed to retain said mask device in position against the action of said biasing means.
 4. A combination as defined in claim 3, wherein said member is a ball, and said frame has an opening adapted to only partially receive said ball, said ball being disposed primarily on the opposite side of said opening from said mask device, said biasing means including a spring urging said ball toward said opening.
 5. A combination as defined in claim 4, wherein said spring is a leaf spring bearing against said ball, and supported on opposite sides of said ball.
 6. A combination as defined in claim 1, wherein said actuating means includes at least one piston-cylinder unit interposed between a portion of said frame and said work-support means.
 7. A combination as defined in claim 6, wherein said piston-cylinder unit includes a cylinder portion having an end thereof in direct engagement with one of said frame or said work-support means.
 8. A combination as defined in claim 1, additionally including a pair of parallel shafts rotatably mounted on said work-support means, each of said shafts having a gear fixed to each of the opposite ends thereof, and also including rack means secured to said frame and inter-engaged with each of said gears.
 9. In combination with a mask device normally having openings for the passage of sprayed material, a fixture for use in conjunction with spray painting comprising: a frame; means on said frame for disengageably supporting and locating said mask with respect to said frame; said means including a carrier normally supporting said mask, a shaft rotatably mounted on said carrier a gear fixed with respect to each end of said shaft, rack means mounted on said frame and in engagement with each of said gears, retaining means maintaining the said gears and racks in engagement, and link means connected to said frame and to said carrier at a position remote from said shaft whereby to laterally remove said mask and carrier from a position overlying said work-support means; work-support means mounted on said frame for vertical movemeNt toward and away from said mask-support means; and actuating means for positioning said work-support means with respect to said mask-support means.
 10. A combination as defined in claim 9, wherein said rack is rectangular and said shaft is disposed adjacent one side thereof, and said link means is connected at a position adjacent the opposite side of said rack, said link means being disposed perpendicularly to the plane of said rack means in the operative position of said rack. 